Reciprocating compressor

Abstract

A compressor has pistons slidably housed in cylinder bores. Respective shoes slide against each of the pistons and a swash plate or cam to convert rotation of the swash plate to reciprocation of the pistons. Each piston has a recess for slidably receiving the shoe. A friction reducing layer containing tin as a major component is formed between the shoe and the piston. Additionally, a tin-based layer may be formed between the shoe and the swash plate.

What is claimed is: 
     
       1. A reciprocating compressor comprising: a cylinder block containing a cylinder bore;   a drive shaft;   a cam connected to and rotated by the drive shaft;   a piston slidably housed in the cylinder bore;   a follower device located between the piston and the cam, wherein the piston is reciprocated via the follower device as the cam is rotated, wherein the follower device has at least one load bearing surface that slides with respect to a cooperative surface; and   a layer containing more than 90% tin by weight formed on at least a portion of one of the load bearing surface of the follower device and the piston, wherein the layer containing tin reduces friction between itself and another surface with which it engages.   
     
     
       2. The compressor according to claim 1, wherein the piston is made of an aluminum-based material. 
     
     
       3. The compressor according to claim 1, wherein the layer containing tin is formed on the entire outer surface of the piston to reduce friction between the piston and the cylinder block and between the piston and the follower device. 
     
     
       4. The compressor according to claim 1 further comprising a layer containing tin formed on the surface of the cam to reduce friction between the cam and the follower device. 
     
     
       5. The compressor according to claim 1, wherein the layer containing tin is formed on the follower device to reduce friction between the cam and the follower device. 
     
     
       6. The compressor according to claim 1, wherein the layer containing tin is formed on the follower device to reduce friction between the piston and the follower device. 
     
     
       7. The compressor according to claim 1, wherein the layer contains at least one metal selected from the group consisting of copper, nickel, zinc, lead and indium. 
     
     
       8. The compressor according to claim 1, wherein the follower device is a shoe having a spherical surface, and the piston includes a recess for slidably receiving the spherical surface. 
     
     
       9. The compressor according to claim 1, wherein the layer contains a solid lubricant selected from the group consisting of a fluororesin powder, a molybdenum disulfide powder, a carbon powder and a boron nitride powder. 
     
     
       10. A reciprocating compressor comprising: cylinder blocks containing cylinder bores;   a drive shaft rotatably supported in the cylinder blocks;   a cam connected to and rotated by the drive shaft;   a piston slidably housed in the cylinder bores;   a ferrous metal cam follower located between the piston and the cam to engage both the piston and the cam, wherein the piston is reciprocated via the cam follower as the cam is rotated; and   a friction reducing coating formed on at least a portion of the cam follower, wherein the coating contains more than 90% tin by weight.   
     
     
       11. The compressor according to claim 10, wherein the coating is formed on the entire surface of the cam follower. 
     
     
       12. The compressor according to claim 10, wherein the coating contains at least one metal selected from the group consisting of copper, nickel, zinc, lead and indium. 
     
     
       13. The compressor according to claim 10, wherein the cam follower is a shoe having a substantially hemispherical shape with a spherical surface, and wherein the piston has a recess for slidably receiving the spherical surface. 
     
     
       14. The compressor according to claim 10, wherein the coating contains a solid lubricant selected from a group consisting of a fluororesin powder, a molybdenum disulfide powder, a carbon powder and a boron nitride powder. 
     
     
       15. A reciprocating compressor comprising: a cylinder block containing a cylinder bores;   a drive shaft located at the center of the cylinder block;   a cam connected to and rotated integrally with the drive shaft;   a piston slidably housed in each cylinder bore, wherein each piston has a load bearing recess;   a follower device located between each load bearing recess and the cam, wherein each piston is reciprocated via the associated follower device as the cam is rotated, wherein each follower device has at least one load bearing surface that slides with respect to the load bearing recess; and   a layer containing more than 90% tin by weight, formed on at least a portion of one of the load bearing surface of the follower device and the load bearing recess of the piston, wherein the layer reduces friction between the follower device and the piston.   
     
     
       16. The compressor according to claim 15, wherein the layer contains at least one metal selected from the group consisting of copper, nickel, zinc, lead and indium.